Just put your card in your reader and hook it to your computer and then open 'My Computer". You should see the drive where it is hooked to. Now go to your folder where the pictures are stored and minimize that page by clicking the button in the top right of your screen next to the red X. You should now be able to see the My Computer screen behind your photos folder. Now just drag the entire folder or just the individual photos on top of the drive where your viewer is instaleed and relase the folder/ photo. It will then copy them back to your memory card. Sounds more complicaed than it actually is.
You can also right click on the folder/picture, then look on the left side of your screen and look for the copy file link and click on that. Then when the drop down box opens select the drive where the reader is attched and select it by clicking on it.